Methods of and apparatus for pyrolysis, or heat processing of pulverized solid fuel having the particle size below 1 mm at high heating rates on the order of 10.sup.3 to 10.sup.6 degrees per second are well known in the art. As compared with those based on slow-rate heating, such methods provide for an increased yield of both solid and liquid products which are subsequently converted into synthetic liquid fuel and into technical and chemical raw materials.
There is known in the art one prior-art method of and apparatus for heat processing of pulverized solid fuel, as disclosed in the USSR Inventor's Certificate No. 335,267.
The above method for heat processing of pulverized solid fuel includes the steps of heating the fuel by a gaseous heat carrier within less than one second to a temperature of 300.degree. to 500.degree. C. at which decomposition thereof begins, followed by heating the fuel by the heat carrier within less than one second to a temperature of 500.degree. to 800.degree. C. at which thermal decomposition thereof grows very intense to form a vapour-and-gas suspension containing solid particles, gas, tar vapours and water vapours, breaking the resultant vapour-and-gas suspension into a solid matter and a vapour-and-gas mixture, purifying and condensing the vapour-and-gas mixture to produce gas, useful liquid products and to separate heavy tars and pyrogenic water therefrom.
The above apparatus for heat processing of pulverized solid fuel comprises a first chamber provided with a means for feeding a charge fuel thereto and with a means for delivering a gaseous heat carrier thereto and discharging it therefrom, the gaseous heat carrier being intended to heat the fuel to a temperature at which thermal decomposition thereof begins, a second chamber successively connected to the first one and provided with a means for delivering the gaseous heat carrier thereto to heat the fuel to a temperature at which thermal decomposition thereof grows very intensive to form a vapour-and-gas suspension, with a means for separating a solid matter from the vapour-and-gas mixture, and with a separator for purifying the vapour-and-gas mixture and feeding it for consideration to obtain gas, useful liquid products and to separate tar and pyrogenic water therefrom.
The above method and the apparatus for practising same, similar to other methods known in the art, and apparatus for fast pyrolysis, provide an increased yield of tar. An overall increased yield of tar naturally involves an increased content of heavy tar therein. Though the combustion heat of the resultant heavy tar (8400 large calories per kilogram) is known to be higher than that of the resultant solid matter (6400 to 6700 large calories per kilogram), its use as fuel presents some difficulties. These difficulties are explained by its being an amporphous plastic substance which is too viscous to be delivered to the consumer through a pipeline and insufficiently hard for transportation in tanks. Thus, in order to use heavy tar as a liquid fuel, it must to be converted to liquid state by heating, which naturally involves additional power, time and labour consumption.
As it is known commonly, said apparatus for processing pulverized solid fuel according to the above method yields solid product in the form of small particles having a porous surface. This causes both an increased hygroscopcity of solid product and its tendency to pulverization. A high hygroscopicity rules out the possibility of storing the solid product outdoors, while its tendency to pulverization makes the working conditions unhealthy and causes considerable losses of fuel. It should be noted that the process yields also such side product as pyrogenic water which contains organic compounds dissolved therein. Prior to disposal, pyrogenic water must be decontaminated, which results in rather high capital and production costs.
It is an object of the invention to develop a method of and an apparatus for heat processing of pulverized solid fuel which enable the production of a solid matter having an increased combustion heat.
Another object of the invention is to provide a method for heat processing of pulverized solid fuel and an apparatus for practising the method which enable heavy tar to be adsorbed by pulverized particles of solid matter.
A further object of the invention is to provide a method of and an apparatus for heat processing of pulverized solid fuel which yield a solid matter suitable for being conveyed by water channels.
A still further object of the invention is the provision of a method of and an apparatus for heat processing of pulverized solid fuel allowing utilization of pyrogenic water which is a side product requiring decontamination prior to disposal.
Among the objects of the invention is also to provide a method of and an apparatus for heat processing of pulverized solid fuel which enable the manufacture of energy-producing fuel in the form of a pulp suitable for being conveyed by water channels.